Synthesis and characterisation of the mesoporous ZnO-TiO2 nanocomposite; Taguchi optimisation and photocatalytic methylene blue degradation under visible light

摘要

In this study, the ZnO-TiO2 nanocomposite was synthesised by a sol-gel method. Using the Taguchi experimental design method, the three parameters of material composition, calcination temperature and calcination time were optimised with respect to the photocatalytic activity of the prepared materials under visible light. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and N-2 adsorption-desorption measurement were performed to characterise the synthesised powders. The sample with the composition of 25 wt.% ZnO followed by calcination at 450 degrees C for 1 h presented the highest photocatalytic efficiency (63%). Among the three synthesis parameters, the statistical results recognised calcination temperature as the most effective factor on the photocatalytic activity of the ZnO-TiO2 nanocomposite. The optical absorption edge of the TiO2-ZnO nanocomposite was detected in the range of visible light and the band gap of the optimal sample was found to be 2.7 eV that is lower than that of P25.